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Scanning Laser
The Dynamic Rotating and Overlapping Delivery System (Scanning) of the
latest generations of Excimer lasers result in smoother ablation surface
free from ridges or grooves. This in turn can lead to a better quality of
the vision after LASIK.
The highly sophisticated excimer laser used light energy to correct focusing problems by vaporizing away a small amount of tissue from the central area of the cornea for nearsightedness and from the mid-periphery of the cornea for farsightedness.
Most surgical laser beams effect tissue by producing heat that burns it, or by producing a shock wave that separates tissue with micro-implosions. The excimer laser is different. It uses a charged mixture of argon and fluorine gases to produce a cool beam of ultra violet light. The beam is unique because it breaks the molecular bonds between cells and vaporizes tissue, one microscopic layer at a time. The excimer precisely sculpts tissue with almost no effect on the surrounding tissue. This ability makes it ideal for changing the shape of the cornea. There are two procedures, PRK and LASIK, which use this unparalleled precision by applying computer controlled pulses of laser light to reshape the eye to correct nearsightedness, astigmatism, and farsightedness.
A simple way to imagine how the laser works is to think of it as placing the curvature from your glasses or contact lenses onto the front surface of your eye, allowing you to see without corrective eyewear.
The following description applies only to the VISX STAR S4 Excimer Laser. The VISX STAR S4 Excimer Laser is the best laser available on the U.S. market today:
The energy output of the excimer laser is precisely controlled by diluting the active argon and fluorine gases within the laser cavity with inert helium gas. This is the coarse control of the energy output of the laser. The fine control of the energy output is acquired by applying varying amounts of high voltage across the laser cavity. In this manner, the energy output of the excimer laser, called fluence, is precisely controlled.
The ultraviolet light of the laser cavity is then directed by mirrors and lenses to the beam homogenizer , then onto the beam shaping modules and finally onto the patient's eye. The mirrors, lenses, homogenizers and beam shaping modules are physically attached to the laser rail. The laser rail is simply a structurally ridged piece of alloy metal that is solidly affixed to the laser cavity so that precise alignment of all components is possible.
The beam homogenizer smoothes out any small inconsistencies in the laser beam energy profile. This is called a rotating dove tail prism. This is also responsible for the scanning characteristics of the VISX Star S4 laser.
The Visx Star S4 with Active Trak and Auto-centering is the most recent and state-of-the-art laser on the US market today, and can be used for both conventional and custom LASIK, PRK, and LASEK. We at Global Laser Vision have been using this since June 2002. The tracking device follows extremely small eye movements enabling the surgeons at Global Laser Vision to fine tune ablations done for PRK, LASIK and LASEK to achieve improved outcomes.
The Visx Star S4 Active Trak uses a video-based tracker composed of two infrared light sources and two cameras that establish a 3-D coordinate system on the eye, allowing it to track an eye in the z-axis ( in and out) as well as in the x- axis (left or right) and in the y-axis (up and down). The cameras are connected to the computer in the laser. When the eye moves to the right, left, up, down or in and out the computer directs the laser beam to move to the right, left, up, down or in and out by the same amount that the eye moved.
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6950 Friars Road
Suite #100
San Diego, CA 92108
18632 Beach Blvd.
Suite #100
Huntington Beach,
CA 92648
800.GET-LASIK
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